Straight bar knitting machines

ABSTRACT

IN A STRAIGHT BAR KNITTING MACHINE, MEANS FOR FORMING LOOP DOUBLINGS AT INFINITELY VARIABLE LOCATIONS IN A LAST KNITTED COURSE OF RIB FABRIC TO REDUCE THE COURSE LENGTH TO THAT REQUIRED FOR NON-RIB FABRIC TO FOLLOW ON, WHEREIN THE USUALLY OPERABLE NARROWING HEAD HAS SELECTOR ELEMENTS CORRESPONDING TO THE NEEDLES AND SELECTIVELY OPERABLE EACH TIME THE NARROWING HEAD IS OPERATED TO RENDER GROUPS OF LOOP TRANSFER POINTS EFFECTIVE ON THEIR CORRESPONDING NEEDLES, TO FORM LOOP DOUBLINGS, AND WHEREIN VARIED GROUP SELECTION IS OBTAINED BY OPPOSITELY ADJUSTED CONTROL BARS UNDER CONTROL OF LEAD SCREWS, AND THE LEAD SCREWS INFINITELY ADJUSTED BY ELECTRIC MEANS INCLUDING A MOTOR AND COUNTER MEANS UNDER CONTROL OF A PUNCHED CHART PROGRAMMING MEANS.

March 9, 1971 BLOOD STRAIGHT BAR KNITTING MACHINES 4 Sheets-Sheet 1 Filed Dec. 9, 1968 R. BLOOD STRAIGHT BAR KNITTING MACHINES March 9, 1971 4 Sheets-Sheet 2 Filed Dec. 9, 1968 March 9, 1971 R; BLOOD 3,56%?

STRAIGHT BAR KNITTING MACHINES Filed D66. 9, 1968 4 Sheets-Sheet March 9, 1971 R. BLOOD 3,568,47

STRAIGHT BAR KNITTING MACHINES Filed Dec. 9, 1968 4 Sheets-Sheet T.

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2 3 rmn nnmnnnnnn nnnn nnnmnnnonnmn nnnnnn nn L J 4o 4/ "26 I .42 L4 as as 4/ US. Cl. 66-89 7 Claims ABSTRACT OF THE DISCLOSURE In a straight bar knitting machine, means for forming loop doublings at infinitely variable locations in a last knitted course of rib fabric to reduce the course length to that required for non-rib fabric to follow on, wherein the usually operable narrowing head has selector elements corresponding to the needles and selectively operable each time the narrowing head is operated to render groups of loop transfer points effective on their corresponding needles, to form loop doublings, and wherein varied group selection is obtained by oppositely adjusted control bars under control of lead screws, and the lead screws infinitely adjusted by electric means including a motor and counter means under control of a punched chart programming means.

CROSS REFERENCES TO RELATED APPLICATIONS Reference is made to- British patent application No. 58,558/ 67 of Dec. 23, 1967, William Cotton Limited, from which priority is claimed.

This invention is for improvements in or relating to straight bar knitting machines and concerns the operation known as loop doubling.

In instances where non-rib fabric is to be knitted onto a rib welt, e.g. for a garment having a rib waistband, the rib welt is formed, of a suitable length to provide for desired resilience, on a number of needles greater than the number of needles on which the non-rib fabric is formed; and in order to reduce the length of the last course of loops of the rib welt to the same length as that of the first course of the non-rib fabric, the operation of loop doubling is effected, wherein at predetermined positions in the length of the last course of the rib welt, adjacent loops are doubled together by loop transference. In a previously proposed method of changing from rib knitting to non-rib knitting, the aforesaid operation of loop doubling is preceded by transfer of the rib loops from machine needles to alternate frame needles which are ineffective during the rib knitting.

Originally said loop doubling was effected by hand and was an undesirably time consuming and tedious task, and several proposals have been consequently made for effecting loop-doubling by automatic operating means.

However these automatic operating means have not been completely satisfactory for at least one reason that the frequency of loop doubling along the course has been limited by the nature of the mechanism and its operation, whereas in practice the frequency of loop doubling is desirably different in certain different garments.

An object of the invention is to provide for loop doubling by automatic operating means at readily changeable frequencies.

The invention provides, in a straight bar knitting machine, loop doubling means, comprising a narrowing head having a row of loop transfer point selector elements corresponding substantially to the row of needles and nited States Patent capable of influencing the transfer points to be effective or ineffective on needles 'each time the narrowing head is operated a plurality of times, and infinitely variable selection control means adapted to render the selector elements effective in groups for each operation of the narrowing head to form, loop doublings and to cause the groups of selector elements to be of any predetermined size to suit the required spacing required for the loop doublings. Conveniently the control means comprises control bar means displaceable along the row of selector elements in amplitudes of movement which change to suit the loop doubling frequency required by predetermined operations of lead screw means under control of counter means. Conveniently also the counter means comprises a predetermining electric impulse counter with automatic resetting which can be manually preset, the count pulses are pro duced by rotation of the lead screw mechanism, and a count complete switch is operated when the preset number of pulses has been registered to cause energizing of a reset coil to reset the counter for automatic repeat operation under final control of a homing switch operated by limit operation of the lead screw mechanism.

The transfer points and selector elements are conveniently as in the arrangement disclosed in US. Pat. No. 3,503,226 which provides a row of flexible transfer points operable in a narrowing head, a row of point controlling elements movable with the narrowing head and displaceable therein between an inoperative position and an operative position deflecting the points into position for cooperating with the needles, a selecting mechanism constructed and arranged for having selective cooperation with the point controlling elements, and means for effecting relative cooperating movements between the narrowing head and the selecting mechanism for selectively operating the point controlling elements. The selecting mechanism includes a row of selector elements shaped to provide a portion for cooperation with the point controlling elements, and, for the present loop doubling, the selector elements are also provided with a portion for cooperation with the control bar means, and a portion for cooperation with a swingable bar for pivotally displacing the selector elements between an ineffective position allowing for the adjusting displacements of the control bar to take place, and an effective position wherein they are selected by the control bar means.

An electric control circuit including the counter means conveniently also includes a programme reader start and stop switch, a start and stop switch, a start and stop position switch, a narrowing machine operated switch, a count complete and incomplete switch, a count svTitch operable from the lead screw mechanism, a reversible electric motor for operating the lead screw mechanism, and relay means for controlling operations of the motor.

The arrangement of the transfer points, the selector elements and the control bar means is conveniently in two halves, the selection control being conveniently started simultaneously on both halves at outer or inner locations and progressing inwardly or outwardly respectively.

The above and other features of the invention set out in the appended claims are incorporated in the arrangement which will be hereinafter particularly described as a specific embodiment with reference to the accompanying drawings in which:

FIG. 1 is a detail cross sectional view of mechanical parts of loop doubling means according to the invention.

FIG. 2 is a detail vie-w of part of FIG. 1.

FIG. 3 is an electric circuit diagram of electric parts of the loop doubling means.

FIG. 4 is a somewhat diagrammatic front view of relevant parts of the machine.

FIG. is a diagrammatic detail front view of part of FIG. 4 at one stage in loop doubling operations.

FIG. 6 is a similar view to FIG. 5 at the second stage in the loop doubling operations.

FIG. 7 is a similar view to FIG. 6 at a third stage in the loop doubling operations.

Referring to FIG. 1, this shows, as in said US. Pat. No. 3,503,226, a Cottons patent straight bar knitting machine represented by a needle bar 1 of bearded needles 2, a sinker bar 3 of sinkers 4, a knocking over bar 5 of knocking over bits 6, a catch bar 7, thread carrier means 8, and a narrowing head, this being represented by blocks such as 9 and rods 10, 11, 12, and side arms such as 13a carrying the rod 11 and mounted on a pivot shaft 13. For operating the narrowing head to have dipping and rising motions about the axis of the shaft 13, as well known in this type of machine for fashioning, the rod 11 is connected by usual link 11a, FIG. 4, to usual cam operating mechanism 11b.

FIG. 4 also indicates that the machine is of multi section type and that usual knitting and fashioning motions are imparted to the needle bars 1 by usual means such as the cam follower lever 1a operable by knitting and fashioning cams 1b, 1c, and the cam follower lever 1a operable by knitting and fashioning cams 1e, 1

Spaced blocks such as 9 FIG. 4, are secured to the rod 11 for imparting, from the cam 11b the usual dipping and rising motions to the narrowing head. To blocks 9 is fixed a half length bed plate 16 to which is fitted a half length row of loop transfer points 17, and to blocks 9 is similarly fixed a half length bed plate 16 to which is fitted a half length row of similar points 17. These points 17 are of bent flexible type comprising, FIG. 1, a downwardly projecting point portion 17a, and an inclined shank portion 17!), which joins with the point portion at a bend 17c. The blocks 9 9 are also secured to the rods 10, 12 respectively which are endwise adjusted by usual means for effecting sideways loop transfers by the transfer points 17 in the usual way.

Secured to the bed plates 16, 16 are guide bars such as 20, 21 having tricks for half length rows of point-controlling blade elements 22, 22 FIG. 4, which are frictionally held such as, FIG. 1, by a cover plate 123, 123a inserted behind flanges 20a, 20b, 21a, 21b of the guide bars 20, 21 and which correspond in length to the row of elements 22.

In the position shown, the narrowing head is in an upper position, and the elements 22, 22 have upper portions 22a, 22a of the elements projecting upwardly from the bars such as 20.

The lower ends 2217 of the elements 22, FIG. l, have a recess 22c and a lower inclined face 22d, and the elements 22 are relatively-slidable in the guide bars 20, 21 first for their inclined face 22d to bear against the bends 17c of the points 17, 17 and deflect the latter and then for the recess 226 to fit on the bends 17c thereof with a releasable engagement.

The elements 22, 22 also have a butt 22c engageable by a reset bar 23 on a rocking rod 24.

Disposed above the narrowing head is mounting means 25 for a main selecting mechanism. In this mechanism is a row of selector elements 26 mounted pivotally on a pivot 27 carried by the means 25 and corresponding to the row of point-controlling elements 22, 22 Each element 26 comprises a first arm 26a depending towards a pointcontrolling element 22 and at its lower end it has a central recess 26]) and which spaces two downwardly projecting portions 26c, 26d. A second arm 262 of each element 26 has an upwardly directed projection 26 which may be for co-operation with pattern bits of a pattern drum PD. A third arm 2611 of each element 26 has a downwardly directed projection 26i and the first arm 26a has a side edge projection 26 Each element 26 is biased by a wire spring 29 of a mounting 30 and bearing against the first arm 26a in a direction urging the upward projection 26 of the .econd arm 26e towards the pattern drum PD.

The second arm 262 also has a tail part 26k for cooperation with a reset bar 31 on a rocking shaft 32.

For co-operation with the downward projection 261 on the third arm 2611 there are two outer narrow control drums such as 33 and associated mechanism, and there may be two inner control drums such as 37 and associated mechanism.

The mechanism thus far described is for forming lace patterns in parallel fabric or fabric with outer and/or V neck fashioning produced on the machine, and no further details are herein described since such further details are not relevant to the present invention.

However the said mechanism thus far described is adapted according to the present invention for loop doubling. For this purpose the arm 2611 of each selector element 26 has a tail portion 26! for co-operation with a pair of conrol bars 40, 41, FIGS. 1, 4, which extend in a direction transverse to the selector elements, i.e. in a direction parallel to the rows of selector elements point controlling elements. transfer points, and needles.

The control bars 40, 41 are each about half the length of a knitting section, and they are mounted in staggered positions for endwise displacements in different paths by being secured to opposite side edges (see FIG. 1) of brackets 42, 43, (see also FIG. 2 for bracket 43) which are secured respectively to different operating rods 44, 45. Conveniently each bracket is slidably engaged by slots 46, 47 with the rod to which the other bracket is secured.

The control bars 40. 41 are disposed and operated to co-operate with left and right hand halves of the row of selector elements. and the arrangement is repeated for other knitting sections, the rods 44, being continuous through those sections and being connected respectively by fingers 48a. 49a to screw nuts 48, 49 of oppositely screw threaded lead screws 50, 51. These leads screws are operated through bevel gearing 50a, 51a, by a motor 52 in a manner to be hereinafter fully described.

In a convenient arrangement, the bars 40, 41 are first disposed by the lead screw mechanism at outermost loca tions where their outer ends extend into the next adjacent knitting sections, and their inner ends are just outside those selector elements in line with selvedge needles, as shown in FIG. 4.

When loop doubling is required, the narrowing head is lowered, and the operating bar 32, FIG. 1, is also lowered thereby to swing all the selector elements 26 to a position where the tail parts 26l are elevated above the level of the control bars 40. 41, and the lead screw mechanism is then operated. as will be hereinafter fully described. to displace the control bars 40, 41 inwardly for a distance equal to the distance between consecutive loop doublings required as indicated in FIG. 5, according to the required frequency for the loop doublings, so that the tail parts 26! of outer groups of the selector elements overlie end portions of the control bars 40, 41. Then the operating bar 31 is raised so that all those selector elements 26 except the outer groups thereof swing back to a position where, when the narrowing head next rises. the associated point controlling elements will be unaffected since their upper ends will engage m the recesses 26]) of the selector elements. However the end groups of the selector elements will be maintained by the control bars in a position where their associated groups of point controlling elements strike the projections 26c of the groups of selector elements, with the result that the associated groups of transfer points 17 are deflected into operative position. Consequently in further operation of the narrowing head to effect a single needle inwards loop transfer operation, end groups of the needle loops are inwardly transferred one needle distance thus forming two outer loop doublings at locations L. L spaced a predetermined distance inwardly from the seivedges.

Following this, the operations are repeated, with the control bars being inwardly displaced for a further distance equal to the first distance, FIG. 6, so that to the first outer groups of selector elements, point controlling elements, transfer points and needle loops, are added second similar groups thereof at the inner sides of the first outer groups, whereby two further loop doublings L L are formed inwardly of the two outer loop doublings L, L and spaced therefrom for the same distance as the outer loop doublings L, L are spaced from the selvedges.

Repetition of the operation is continued in this manner each time including further groups of the parts at the inner sides of the last operated groups, thereby forming further loop doublings such as L L FIG. 7 all equally spaced, until an inner limit position is reached and the operations cease.

An important advantage of this arrangement is that, since the spacing and therefore the number of the loop doublings depends entirely upon the displacments of the control bars and these displacements are widely variable simply by stopping the lead screw mechanism after one or any practical unit of rotation, the loop doublings can be formed of any practical number and with any practical spacing to suit various alternative requirements.

For this purpose an electric control system is employed according to FIG. 3 in conjunction with a programming means such as a punched card and feeler operated card reader micro switches adapted in a known manner to cause the required fashioning motions of the machine from fashions holes in the pattern card but at this stage a clutch 54 is disengaged and a brake 53 is applied.

The narrowing machine next lowers so that the switch NM moves to the down position in which, through a closed count incomplete side of a two way count control switch CC it causes the clutch 54 to engage and the brake 55 to release whereby the lead screws 50, 51 commence rotation to displace the screw nuts 48, 49 from outer positions inwardly, for inwardly displacing the control bars 40, 41 as hereinbefore described.

The rotation of the lead screws 50, 51 is imparted to an indexing plunger device 56 which operates a count micro switch CS to register the movements by pulses of the counter PC. When the preset number of pulses has been registered by the counter PC, the count control switch CC automatically changes to close the count complete side. This causes the clutch '54 to disengage and the brake 55 to operate thereby stopping rotation of the lead screws 50, 51.

The narrowing machine then operates for the required inward loop transference, and it will be understood that the size of the groups of loops transferred is governed by the number to which the counter PC was preset. Consequently the size of the groups of loops transferred and the frequency of the loop doubling is readily variable between wide limits simply by different pre-settings of the counter PC to suit requirements.

In the electric control circuit there is a predetermining impulse counter, for example, of the type known by the trade name Sodeco and having electric count-resetting means of a known construction. This counter is pre-set, before loop doubling operations are required, by manually rotating control discs of digit-counting mechanism, to set up a predetermined count to suit the required spacign of loop doubling to be made.

Assuming that a fashions hole has been thereafter detected, this will, by the known mechanism, cause repeat fashioning motions of the narrowing head for a required number of times equal to the number of loop doublings required, and during this time the card reader microswitch C.R. will be in its operated down position. This closes circuit to a relay RLM whose contacts RLM13 start the reversible motor 52 which is connected, through a gear box 53 containing the aforesaid level gearing, a disengaged clutch 54, and an applied brake 55, to the lead screws 50, 51.

The first lowering of the narrowing head operates the switch NM to the down position which closes circuit, through a count control switch CCS to an operating coil of the clutch 54 to engage the latter, and which opens circuit through open contacts of the switch CCS to the brake 55 to release the latter. Thcreupon the motor 52 drives the lead screws 58, 51 which displaces the control bars 44, 45 in the required progressive manner.

The counter includes a counting coil CC which is connected to the normally closed contact C2 of count switch CS and to the supply. During the rotations of the lead screws 50, 51, the count switch CS is operated by a pulsing device 56 driven by the motor 52 in synchronism with rotations of the lead screws 50, 51 to operate the counting coil CC in the counter thereby to rack on digit drums of the counter PC to progressively reduce the count by one for each rotation of the lead screws 50, 51.

The last count motion operates the count control switch CCS which opens circuit to the clutch 54 to disengage it and closes circuit to the brake 55 to apply the brake so that rotation of the lead screws 50, 51 and consequent adjustments of the control bars 44, 45 is stopped. Thus the control bars have had imparted to them a first adjustment to an extent governed by the pre-setting of the counter PC.

At this'stage the narrowing head is operated by usual means for sideways loop transference to form the first loop doublings, followed by usual raising of the narrowing head.

The last operation of the counting coil CC causes operation of a reset switch which closes circuit to a reset relay and this introduces a reset coil RC which causes return of the digit drums to the original number, all in known manner, for the counter PC.

Since the switch CR remains down for further fashionings, the motor 52 continues running, and when next the narrowing head lowers it again operates the switch NM to the down position, whereby the clutch 54 is re-engaged and the brake 55 is released, so that the lead screws 50, 51 are again rotated to again adjust the control bars 44, 45. During this time the count switch CS is again operated to progressively reduce the count in the counter to zero so that a second adjustment similar to the first is imparted to the control bars 44, 45.

This process repeats automatically until the required number of fashionings, or loop doublings, have been made. At this stage the programming chart is caused by the programming control to rack on whereby the switch CR is return operated, and this opens circuit to the relay RLM whereby the contacts RLM1-3 open to stop the motor 52. In addition, the last motion of the control bars operates a limit switch HA to close circuit to a relay RLR. This operates contacts RLR 3 to re-close circuit to the relay RLM through the operated limit switch HA and the returned switch CR, to restart the motor 52, and it also closes contacts RLR/4 which causes the clutch 54 to disengage, and the brake is released through the operated limit switch HA. Also operated are contacts RLR/ 13, which causes reversal of the motor whereby the lead screws and control bars are returned to their original setting.

The last movement of the control bars causes the switch HA to change to the home position whereby the relays RLR and RLM are de-energized so that the clutch 54 is disengaged and the brake 55 is applied.

At this stage a complete set of loop doublings have been provided and the system is ready for subsequent complete repeat operation instigated when required under control of the programming means.

Although the foregoing particular description relates to a system in which the control bars 40, 41 are displaceably adjusted from outer positions inwardly, it is within 7 the scope of the invention for the control bars 40, 41 to initially dispose at an inward position nearly reaching the centre of the knitting section from which they are displaceably adjusted outwardly in like but reverse manner to that described, by reversing the direction of the motor. An advantage of this arrangement is that when loops have been doubled they are not thereafter removed from the needles so that strain on the loops is minimized.

What is claimed is:

1. Knitting machine linear adjusting means comprising in combination, an adjusting screw, a screw nut on said screw for connection to a member to be linearly adjusted and inhibiting rotation of said screw nut, drive means connected for rotating said screw to obtain continuous linear adjustment of said screw nut means and said member, and electric control means for said drive means comprising, in an electric circuit, program controlled means for starting said drive means, drive interrupting means including an interrupting switch operable by a periodically operating machine part for producing interruptions of the continuous linear motion of said member in periodical manner, a manually presettable impulse counter and reset means operably connected to said drive interrupting means for periodical operation of said counter and reset means, and a counter pulsing device operable in synchronism with rotations of said screw for periodical counting by said counter and reset means each time to the limit of the preset count so that periodical linear adjustments of said member are of a magnitude which is variable by variable presetting of said counter and reset means,

2. Means as claimed in claim 1 having a reversible electric motor connected for rotating said screw, program controlled electric starting switch and relay means connected for starting said reversible electric motor, an electric clutch and electric brake connected to said motor and operable by said interrupting switch, and electric stop switch and relay means connected for operation by a limit adjustment of said member to reverse operation of the motor and reset said member.

3. A straight bar knitting machine loop doubling mechanism comprising, in combination, a narrowing head which is program controllable for repeat operation, a row of defiectable loop transfer points in said narrowing head. a row of selector elements operable in said narrowing head for deflection of said loop transfer points between effective and ineffective positions in a selective manner, control bars which are endwise displaceable into operable co-operation with progressively changing numbers of said selector elements for selection of the loop transfer points associated therewith in groups which change progressively along the row thereof, to provide for spaced loop doublings, and program introduced control means for said control bars comprising power-operated adjustable screw means to which said control bars are connected and including a lead screw, means operable under control of the repeat operations of the narrowing head for progressively adjusting the screw means and control bars each to the extent of a plurality of rotations of said lead screw, and counter means operable under control of said repeat operations of the narrowing head for controlling the magnitude of said progressive adjustments such that the spacing of said loop doublings is variable by variable presetting of said counter means.

4. A straight bar knitting machine having loop doubling mechanism comprising a narrowing head which is program controlled for repeat operation, individually controllable loop transfer points in said narrowing head, oppositely adjustable control bars for selective control of said points, an adjustable lead screw mechanism having oppositely adjustable screw nuts to which said control bars are connected respectively and an oppositely screw threaded lead screw mounting said screw nuts, and electric control means for controlling said adjustable screw mechanism comprising in an electric circuit, programmed controlled introducing switch means, a reversible electric motor connected to said switch means and to said lead screw, drive interrupting means connected between said motor and said lead screw, an interrupting switch connected to said drive interrupting means and periodically operable by repeat operations of said narrowing head, for producing interrupted rotations of said lead screw and interrupted linear adjustments of said control bars in opposite directions, such that spaced loop doublings are formed by selected loop transfer points, an electric pulsing device operable in synchronism with rotations of said lead screw. and a manually presettable counter and reset device connected to said interrupting switch and to said pulsing device for providing repeat operation each time the limit of a preset count is reached such that the magnitude of the linear adjustments of said control bars and the spacing of said loop doublings is variable by variable presetting of the counter and reset device without varying the main programming control of the machine.

5. A knitting machine comprising in combination, a periodically operable narrowing head with loop transfer points, adjustable lead screw mechanism comprising an oppositely screw-threaded adjusting screw, a pair of screw nuts on said screw-threaded points of said screw respectively for connection respectively to first and second elongate members inhibiting rotation of said screw nuts, and required to be linearly adjusted in opposite directions for selective control of said loop transfer points, drive means connected for rotating said screw to obtain continuous linear adjustment of said screw nuts and said members in opposite directions, and electric control means for said drive means comprising, in an electric circuit, machine programming controlled means for starting said drive means, drive interrupting means including an interrupting switch operable by said periodically operable narrowing head for producing interruptions of the continuous linear motion of said member in periodical manner, a manually presettable impulse counter and reset means operably connected to said drive interrupting means for periodical operation of said counter and reset means, and a counterpulsing device operable in synchronism with rotations of said screw producing output in accordance therewith for periodical counting by said counter and reset means to the limit of a preset count so that periodical linear adjustments of said members in opposite directions for selective control of said loop transfer points are of a magnitude which is variable by variable presetting of said counter and reset means.

6. In a straight bar knitting machine, loop doubling means comprising, a narrowing head which is program controllable to have a predetermined number of loop transfer motions in a single course, loop transfer points carried by the narrowing head which are selectively individually controlled to be effective and ineffective for loop transference, selector elements having butts and carried by the narrowing head in a manner for selective operation to eifect selection of the loop transfer points, selection means including a pair of control bars which are endwise displaceable for operable association with different groups of said selector element butts for reflecting selective operation of the selector elements in different groups for the loop transfer points to form spaced loop doublings, and variably pre-settable selection control means operably associated with the pair of control bars for controlling the said bars to cause the groups of selector elements to be of a variable predetermined size to suit the spacing required for the loop doublings.

7. A straight bar knitting machine having a successively operable narrowing head, separately controllable loop transfer points in two end-to-end rows in the narrowing head, upwardly and downwardly movable selector elements arranged in two end rows in the narrowing head for acting on the loop transfer points, butts on each row of selector elements, first and second control bars one for each row of selector element butts, first and second oppositely threaded adjustable screws connected to the first and second control bars respectively for producing progressive opposite displacements of the control bars so that said control bars act on the selector element butts to render progressively different groups of the loop trans fer points effective and other different groups thereof ineffective for use during successive operations of the narrowing head, and an electric system for controlling the control bars and including a reversible motor with releasable clutch and brake connected to the adjustable screw for rotating the adjusting screw at adjusting intervals under control of the narrowing head, a manually prcsettable counter, and a count pulsing device operably connected with the drive to the adjustable lead screw for predetermining the extent of rotation thereof at each adjusting interval.

References Cited UNITED STATES PATENTS 10 RONALD FELDBAUM, Primary Examiner US. Cl. X.R. 

